In advanced aircraft and aerospace systems, there is a need for high temperature thermoset resins for matrix and adhesive applications. Such resins, because of the complexity of structure, high glass transition temperature needed and high temperature thermooxidative stability required, have critical processing difficulties when required to conform to the state-of-the-art processing criteria. OSHA requirements negate processing such materials from solvent base systems, thereby necessitating fabrication of the resins via melt techniques.
As disclosed in U.S. Pat. Nos. 3,966,729 and 4,147,868, recent advances in matrix and adhesive resins have resulted from the discovery of a family of new phenylquinoxaline resins terminated by primary acetylene groups. The acetylene moiety can be thermally homopolymerized between 200.degree. and 250.degree. C. to form a moisture insensitive, high temperature resin system. Although the materials show excellent resistance to heat and environmental surroundings, the oligomers lack the necessary flow for melt processing because of their high glass transition temperatures (Tg = 140.degree.-170.degree. C.).
It is a principal object of this invention, therefore, to provide reactive diluents which, when mixed with certain selected phenylquinoxaline oligomers, provide compositions having good flow characteristics.
Another object of the invention is to provide reactive diluents which are completely compatible with certain selected phenylquinoxaline oligomers.
A further object of the invention is to provide reactive diluents which on thermal treatment co-cure with certain selected phenylquinoxaline oligomers.
Other objects and advantages of the invention will become apparent to those skilled in the art upon consideration of the accompanying disclsoure.